Method of making abrasive castings



June 1l, 1940.l w SIEGER- r 2,204,453

' Tuo 0F MAKING ABRAsIvE CASTINGS JMA Patented June 11, 194015' f'rATENT oi-FICE METHOD oF MAKING AaAsIvE CASTING Walter Sicgert, Chicago, Ill., assignor to Howard Foundry Co., Chicago, Ill., a corporationV of Illinois Application July 30, 1938, Serial N0. 222,204

1 Claim. (Cl. 22-202) Thisk invention is directed to' the making of floor platespstair treads, or the like, which are designed `to provide an abrasive surface to prevent wear'and slipping; and the method consists essentially in embedding into the metal surface of abrasive or gritty particles which are anchored within the metal during the pouring operation and lie substantially flush with the metal surface or in slightly protuberant relation thereto so'as to afford a frictional grip which will prevent slipping and at the same time protect the softer metal from wear during a long period of time.

The method of the present invention eliminates the use of any form of cementive material and is designed to so distribute the abrasive particles Within the mold asto provide for the inflowing of the metal around the separate particles in such a way that each one will be permanently retained within a metal socket so that displacement will be prevented.

Further objects and details will appear from a' description of the invention in conjunction with the accompanying drawing, wherein- Figure A1 is a sectional elevation of a mold with the pattern in place to provide the necessary indentations in the surface of the mold:

Fig. 2 is a similar view showing the pattern,

removed and the gritty particles distributed in position within the mold to receive the charge'of metal;

Fig. 3 is an enlarged detail showing the inden in which the metal flows around theparticles to embed the same;

Fig. 6 is a sectional detail showing the manner of control throughthe completed casting to provide for the screw holes; and

Fig. 'I isa perspective view of a corner of the "tion the molders sand i is packed into the drag II of the mold in the usual manner. A pattern I2 is then prepared by applying to the lower face of the pattern a roughened surface I3 which may be provided by the adherenceto the pattern of a facing of abrasive cloth orA paper having gritty particles of relatively fine grit, as for instance No. 24 grit, adhereing to the surface, although if desired the relatively fine particles may be adhered directly to the surface of the-pattern.

When the pattern is impressed into the sand within the drag, the roughened surface will form irregularminute pockets or indentations Il (Fig.

3), the size of which will be determined by the grade of the grit employed.

The pattern is also provided with recesses I5 of conical formation, which are of a size and shape to provide for the heads of the screws or bolts to be employed in securing the completed casting in the intended position.

The cope vof the mold I6 is provided with a sand filling II adapted vto lie flush with the pattern and with the surface of the sand in the drag, with the usual pouring apertures I8 and I9 formed through the sand. After the surface of the sand has been indented in the manner stated, and after .the pattern has been removed, gritty' particles of Carborundum, Alundum or silicon carbide or the like, of considerably coarser grit, as for instance No. 16 grit, are sprinkled and evenly distributed over the surface of the mold in such a way as to cause the coarser particles to be socketedor retained within the indentation I4, which latter, however, rare of lesser volume than the gritty particles 20, so that the tips only of the latter will be socketed Within the indentations, as

in Fig. 4, allowing the larger mass of each particle to overlie or overhang the edges of the socket which provides for the underflowing of the metal when' the latter is poured into the mold. -Prior to the closing of the mold, the entire space bearing the grit may be sprayed with silicate of soda, or any other form of binder material, and then dried with a torch, so as to secure thegrit to prevent its being moved out of place by the on rush of molten metal.

As shown in Fig. 4,-a part only of the indentations will be fllled by the gritty particles, leaving open indentations interspersed therebetween, with the result that when the metal is poured to provide the body 2| of the casting, the metal will ow freely into the unoccupied indentations and afford points or projections 22 which lie in substantially flush relation to the points of the gritty particles, so that the completed surface will present the character of a roughened or serrated metal surface interspersed by the tips of the gritty particles, which latter, however, are permanently anchored and embedded by the surrounding metal, so that displacement will be impossible.

In the formation of the mold, the recesses I5 in the pattern will result in projections 23 in the mold, which projections extend very materially above the roughened or abraded surface,

` and these' projections will form conical recesses 24 in the casting, which, however, will be free vfrom the presence of gritty particles, so that thereafter a screw hole or bolt hole 25 may be readily drilled through the metal without bringing the drill surface into contact with the gritty particles, which if present would seriously interfere with the drillingl operation.

The casting producediin the manner stated presents a roughened surface throughout which the metal points and the gritty points will be distributed with substantial uniformity, which surface, however, will afford high resistance to wear and slipping, but without exposing the tips of the gritty particles at a higher level than the metal, so that the former will be protected against sharp impact which might tend to break away the projecting points, which though much harder than the metal itself are of somewhat brittle character, with the result that the wearing sur-v grade for the embedded material, the latter will be so disposed that the metal will underflow theA body of eachvparticle to a suflicient extent to provide a rigid and permanent socket therefor without the provision of any form of coating or adherent substance, which thereby simplifies and improves the casting operation and at the same time results in a much superior product.

As shown, the grade of gritty material employed rst for the pattern and later for the embedded particles, and the manner of distribution of the latter, is such as to permit the metal tips of the gritty particles to project in equal degree to the wearing surface, but variations in the selection of the intended grades of material may be made, with a resultant variation in the proportions of metal and grit exposed at the sur--l face level. That is to say, if desired, a preponderant exposure of metal or a preponderant exposure of grit can be provided for, with like variations in the frictional character of the resultant surface.

I claim:

The method of making abrasive castings which consists in forming a mold about a pattern having closely spaced relatively small protuberances throughout its surface to produce corresponding small indentations in the surface of the mold, sprinkling in the surface of the mold particles oi abrasive material and partially socketing the same Within certain indentations of the mold, said particles being of a size when socketed to project over adjacent indentations, whereby intervening indentations are left empty and thereafter pouring the metal into the mold in position to underflow and embed the bodies of the abrau 

